In a photographic optical device which is mounted on a cell phone or a digital camera, a laser beam pointer, or an optical instrument such as a portable projection display device or a projection display device for car, shake is easily occurred in its optical axis when shake or external vibration is transmitted.
In order to prevent this problem, a photographic optical unit which is used, for example, in a portable photographic optical device has been proposed in which a movable module is supported by a fixed body through an elastic member, an actuator utilizing a piezo-electric element is structured on each of side faces of the movable module, and the movable module is swung around an X-axis and a Y-axis which are perpendicular to an optical axis direction (Z-axis direction) of the actuator on the basis of detection result of a shake detection sensor to correct the shake (see Japanese Patent Laid-Open No. 2007-129295).
Further, as a photographic optical unit capable of correcting shake at the time of photographing, another optical unit has been proposed which includes a movable part on which a lens and an imaging element are mounted, a pivot part which is fixed to a base and abutted with a bottom face of the movable part, a flat spring which is fixed to the base and swingably supports the movable part, and a swing mechanism for swinging the movable part (see, for example, Japanese Patent Laid-Open No. 2007-310084). In this optical unit, the swing mechanism is structured of a drive coil and a drive magnet, and the movable part is swung by a drive force of the swing mechanism with the pivot part as a supporting point to correct the shake.
Further, in this optical unit, the flat spring is provided with a fixed piece which is fixed to the base, an outer frame piece which is connected with the fixed piece through an X-axis deformable part, and a support piece for the movable part which is connected with the outer frame piece through a Y-axis deformable part. The X-axis deformable part and the Y-axis deformable part are twisted when the movable part is swung. In this optical device, the flat spring is fixed to the base in a resiliently bent state so that pressurization is generated for surely abutting a tip end of the pivot part with the bottom face of the movable part.
However, in the case that the actuator utilizing a piezo-electric element is used like the structure disclosed in the above-mentioned former Patent Reference, the fixed body and the movable module are mechanically connected with each other through the actuator and thus much labor is required for assembling and vibration resistance may be low. Further, even in a case that the swing mechanism is structured of a drive coil and a drive magnet, it is insufficient to correct shake with a small torque and a quick response.
Further, in a market of a portable apparatus such as a cellular phone, the size of a portable apparatus has been remarkably required to be made smaller and thinner and, as a result, a photographic optical unit which is mounted on the portable apparatus has been also required to make smaller and thinner. However, when the size of the photographic optical unit is reduced, an arrangement space of the drive coil and the drive magnet for swinging the movable part which is provided with a lens and an imaging element is restricted and, therefore, it is difficult to obtain a sufficient drive force for swinging the movable part.